|First, your embedded links seem to bring up a "Fraud Warning" about a web page that has been reported for distributing malicious software.|
It is not clear in your post why you are configuring a ad-hoc network for the laptop running ICS. If the purpose is to use the laptop as an Internet router for your other computers, wouldn't it be better to configure it as a wireless access point and have the other computers configured with the laptop as the Internet gateway?
Your story about your sister experiencing some stranger actually speaking to her through the speakers in her laptop computer is bizarre. If this is true, and it is not something she initiated, then it would imply that somebody else is in control of her computer. I hope she doesn't have any personal/sensitive information on it.
This is not meant as an argument about your budget constraints, that's a personal matter which you should deal with as you feel is best, but the price of a basic wireless router is less than the monthly cost of your Internet connection. It seems a trivial sum when compared to the anguish and fustration you are reporting.